• 한국자동차공학회논문집
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• 제14권3호
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• pp.75-80
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• 2006

Since air pollution has become a globally critical issue and exhaust emissions from automobiles cause a major source of air pollution, many countries including advanced countries have stipulated stringent emission regulations. Particularly in diesel vehicles, NOx and particulate matters exhaust in significant amounts even though diesel vehicles provide merits in aspects of higher thermal efficiency and lower $CO_2$. To reduce Particulate matters and NOx, after-treatment technology such as filter trap, oxidation catalysts and EGR has been applied. This test was conducted on the effect of continuous regeneration diesel particulate filter and cooled-EGR, and 15ppm low sulfur diesel was used as a test fuel. Exhaust emissions, PM, NOx, CO, HC and Soots were measured and compared under D-13 and D-3 modes.

• The Korean Journal of Ecology
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• 제21권5_1호
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• pp.449-456
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• 1998

This study was carried out to investigate the characteristics of acid deposition by stemflow, throughfall, rainfall and $SO_{2}$ in the industrial, urban and rural areas where were affected by the acid rain areas air pollution in Pinus thunbergii than Quercus spp. forest. As the stemflow pH in industrial and urban area were lowed that of rural area, the result industrial and urban, and correlation of negative ($r=-0.9415^{**}$) between pH and EC. The concentration of acid ion by stemflow, throughfall, rainfall were high $SO_{4}^{2-}$ ion at industrial areas, especially of $NO_{3}^{-}$ ion at urban areas. The concentration of basic ion all rain fall were high $Ca^{2+},\;Na^{+}$ ion at industrial areas, but there were high $Ca^{2+}$, $Na^{+}$ ion at urban areas. The concentration of $SO_{2}$ at survey areas were high $SO_{2}$ concentration at industrial and urban areas, but there was low at rural areas. There was correlation of negative ($r=-0.8007^{**}$ between pH and $SO_{2}$ concentration at survey areas. Soil acidity was also affected by stemflow and showed sigificantly low pH in industerial and urban areas.

• Ocean Science Journal
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• 제40권1호
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• pp.1-10
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• 2005

Variations in species diversity and abundance of polychaete taxocenes that occurred in 1980-1989 under different contamination levels of bottom sediments were studied in three areas of Peter the Great Bay. The most polluted area was shown to be the Golden Horn Inlet where contaminant contents in the bottom sediments exceed the threshold values of negative biota alterations. Amursky Bay is characterized by a moderate level of contamination, while Ussuriysky Bay has the lowest level of contamination. Pollutant contents vary considerably within the same areas and their separate patches are polluted differently. An integral index characterizing the contamination of bottom sediments is proposed. This index is an average grade of the rank value of contaminant contents in sediments. The index was used to compare the contamination level and data on polychaete species diversity and abundance. The highest species diversity of polychaetes is found in the least affected zones. Monotonous decrease of the species number, as well as decrease in the indices of diversity and evenness, is correlated with pollution level increases. Significant growth of the average polychaete biomass and polychaete density is observed in the case of an increase of contamination from low to moderate levels. Conversely, the biomass and abundance of polychaetes decline following an increase in contamination.

• 한국환경보건학회지
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• 제31권3호
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• pp.215-220
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• 2005

The atmospheric transportation and dispersion processes of air pollutants are important issues in dealing with air pollution problems. Air pollutants originated from biological and anthropogenic activities are not only limited to the local emission sources, but could also be transported and dispersed to other regions by synoptic weather systems. Besides, the complexity of topography of central Taiwan helps accumulating air pollutants to promote high-concentration episodes. The techniques of tethersonding were applied to monitor the vertical profiles of winds, air temperatures and humidity, as well as to collect air samples, to be analyzed for pollutants $(O_3,\;NO_2,\;NO\;and\; NMHC)$ from the ground up to 1000m. A time period of about one week, 19-26 October 2002, was chosen as the sampling period due to the high frequency of episode occurrence in autumn based on the past records. Associating with the analysis of weather patterns, the atmospheric characteristics over high-concentration areas can be resolved in more detail. The result of the tethersonding studies showed that weak northerly sea breeze (with thickness about 300m) with low wind speed (about 1 to 2 m/sec) could help develop high ozone concentrations in the down-wind areas. It is also important to have a built-up aloft of precursors and ozone to develop high concentration on the previous day.

• 한국환경과학회지
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• 제16권2호
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• pp.227-232
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• 2007

Water pollution in enclosed water bodies such as lake and river has become a serious problem over the world. Domestic wastewater is responsible for more than 60 % pollution load in public water area in Korea. Effluent of the treated domestic wastewater at low removal level is abundantly fed rivers and lakes and thus be an serious cause of lake pollution. Therefore, effective implement of domestic wastewater treatment in basin of lake and river must be prepared. The septic tank is one of the effective domestic wastewater treatment equipment and used in individual treatment for a unit of household, The purpose of septic tank as biological treatment system is simultaneously to remove BOD, T-N, T-P and reduce turbidity from influent. Accordingly, the appropriate control of functional microorganisms is important subject for the establishment of stability and economy of the biological treatment method. Especially, microanimals as a high-ranked microorganisms of food-chain are important, because microanimals control the other microorganisms especially various bacteria and effect on function of treatment. Therefore, it is necessary that functional predator like rotifers are attached in wastewater treatment process. In this study, the methods for attachment high density the rotifer to and improvement of transparency in the effluence by a dense rotifer was examined using laboratory scale biological treatment reactor simulated septic tank and real one.

• Fisheries and Aquatic Sciences
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• 제2권2호
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• pp.167-171
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• 1999

This study was designed to develop biomarkers of coastal pollution using biochemical indices of flounder (Paralichthys olivaceus) by changes in lactate dehydrogenase (LDH) activity in the serum and cholinesterase activities in brain membranes. For this purpose acetylcholiesterase (AChE) activity, butyrylcholinesterase (BChE) activity, LDH/AChE ratio and LDH/BChE ratio of cultured flounders at 5 different sites on the southern coast of Korea were compared to those of wild flounders caught in the Pohang, eastern coast of Korea as a control group. Relatively high LDH activities were measured in the serum of flounders cultured on the southern coast of Korea (0.101-0.145 unit) than those in the Pohang control group (0.093 unit). AChE activities were significantly low $(about\;10-20\%)$ in brain membranes of cultured flounders compared to those in the Pohang control group. The ratios of LDH/AChE and LDH/BChE were consistently higher $(136-178\%,\; 155-214\%)$ in cultured flounders than those of Pohang control group. Thus, we propose that the ratios of LDH/AChE and LDH/BChE in flounders could be applicable for the diagnosis of marine pollution.

• 전기학회논문지P
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• 제65권1호
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• pp.53-56
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• 2016

Because of the low pollution resistance of the porcelain electrical insulator itself, in this work the anti-pollution performance of insulator was improved by using the functional coating. The ceramic substrates that components were same as the porcelain electrical insulator were used in this experiment. The functional films were coated on the ceramic substrate by using a spray coating method, and then the coated substrate were annealed under different coating condition such as natural curing and annealing temperature of $200^{\circ}C$, $300^{\circ}C$ and $400^{\circ}C$. Then, the contact angles of the coated surfaces were measured and the minimum angle ($8.3^{\circ}$) was obtained at $400^{\circ}C$. The anti-contamination properties were measured, revealing that as the contact angle decreased, the anti-contamination properties improved. The hardness and adhesion were small at the natural curing condition however the excellent mechanical properties were obtained under higher temperature annealing.

• 한국환경과학회지
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• 제26권2호
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• pp.159-172
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• 2017

Asthma deaths in Seoul peaked on the third, fifth, and second days after the PM concentration exceeded the daily average concentration standard. We classified the synoptic meteorological conditions, based on the days involving such cases, into three categories. Type 1 included the meteorological condition likely to cause high air pollution concentrations in the leeward region, the dominant wind direction of which is the northwest. Type 2 included the meteorological condition likely to cause high air pollution concentrations due to the weak wind velocity under stable atmospheric conditions. Type 3 was when the passage low atmospheric pressure and the expansion of high atmospheric pressure occurred at the rear, indicating a meteorological condition likely to cause high air pollution, in certain regions. Type 1 occurred 11 times, with high concentrations of over $100{\mu}g/m^3$ being observed in the southeastern part of Seoul. Type 2 occurred 24 times, often accompanied by a PM concentration of $100{\sim}400{\mu}g/m^3$. Type 3 occurred 11 times, and was accompanied by several days of yellow dust that accounted for the highest concentrations.

• 한국물환경학회지
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• 제33권1호
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• pp.97-106
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• 2017

In this study, the characteristics of nonpoint source pollutant loads from separate sewer overflow (SSO) and combined sewer overflow (CSO) were evaluated during 2016 in Namyangju city, Korea. Five rainfall events were monitored during 2016 with ranging from 14.5 mm to 121.5 mm. The runoff ratio of CSO was higher than that of SSO because only design volume of maximum sanitary sewer ($1Q_h$) was transported and treated and $2Q_h$ was overflowed to waterbody during rainy day although combined sewer system was designed to transport $3Q_h$ to treatment system. The event mean concentrations (EMCs) and pollutant loads from CSO were higher than those from SSO. BOD and COD of CSO, and TOC and TN of SSO represented distinct first flush phenomena. The inadequate management in combined sewer system from which the untreated $2Q_h$ from CSO was overflowed to waterbody during rainy day could influence on high pollutant loads and first flushing. Treating $2Q_h$ from CSO, source control such as low impact development, and treating outflow from SSO were strongly recommended to control non-point source pollution in urban area.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2007년도 학술발표회 논문집
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• pp.454-458
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• 2007

Nonpoint source (NPS) pollution is a serious problem causing the degradation of soil and water quality. Concentrated overland flow is the primary transport mechanism for a large amount of NPS pollutants from hillslope areas to downslope areas in a watershed. In this study, a soil erosion model, nLS model, to identify transitional overland flow regions (i.e., ephemeral gully head areas) was developed using the kinematic wave overland flow theory. Spatial data, including digital elevation models (DEMs), soil, and landcover, were used in the GIS-based model algorithm. The model was calibrated and validated using gully head locations in a large agricultural watershed, which were identified using 1-m aerial photography. The model performance was better than two previous approaches; the overall accuracy of the nLS model was 72 % to 87 % in one calibration subwatershed and the mean overall accuracy was 75 to 89 % in four validation subwatersheds, showing that the model well predicted potential transitional erosion areas at different watersheds. However, the user accuracy in calibration and validation was still low. To improve the user accuracy and study the effects of DEM resolution, finer resolution DEMs may be preferred because DEM grid is strongly sensitive to estimating model parameters. Information gained from this study can improve assessing soil erosion process due to concentrated overland flow as well as analyze the effect of microtopographic landscapes, such as riparian buffer areas, in NPS control.